This invention relates to a disposable body fluid absorbent wearing article such as a disposable diaper, an urine absorbent pad or a sanitary napkin.
FIG. 9 of the accompanying drawings is a perspective view showing a liquid-pervious flexible composite sheet 100 described in Japanese Patent Application Publication No. 1999-217453A. This composite sheet 100 is adapted to be used as a liquid-pervious topsheet covering a liquid-absorbent core in a body fluid absorbent wearing article. The composite sheet 100 comprises a plastic sheet 101 and a fibrous layer 102 bonded to the lower surface of the sheet 101. The sheet 101 has a plurality of flat zones 108 extending in parallel one to another in Y-direction and a plurality of opening arrays 111 extending in the Y-direction, each of the arrays comprising a plurality of openings 109. Each of the flat zones 108 are formed along its edges 118 with rising portion 112 extending upward from the flat zone 108. Upper edge 117a of the rising portion 112 undulates along the edges 118. In the case of the disposable diaper using this composite sheet 100 as its liquid-pervious topsheet, a quantity of body fluids discharged on the flat zones 108 of the composite sheet 100 will flow through the troughs defined between respective pairs of the adjacent individual rising portions 112, 112 into the openings 109 and then will be absorbed by the core underlying the composite sheet 100. The plastic sheet 101 has its initial shape held by the fibrous layer 102 and therefore it is not apprehended that the sheet 101 might be wrinkled and consequently a plurality of the openings 109 might be substantially closed. The composite sheet 100 preferably has a breathability of 5xcx9c700 cm3/cm2xc2x7sec as measured in accordance with prescription of JIS L 1096 and a water-resistance of 0xcx9c200 mm as measured in accordance with prescription of JIS L 1092.
The flexible composite sheet of prior art is certainly advantageous in that a plurality of projections, i.e., individual rising portions serve to offer a cloth-like touch in spite of being made from plastic sheet material and a plurality of openings serve to improve the liquid- and air-permeability. In addition, this composite sheet is hydrophobic in its flat zones as well as in its rising portion so that a cloth-like touch free from wetness may be maintained even after body fluids have been discharged thereon. However, these flat zones and rising portion are rather repellent against body fluids and may deteriorate the desired liquid-permeability of the composite sheet.
It is an object of this invention to provide a disposable body fluid absorbent wearing article that maintains a dried cloth-like touch and the high liquid-permeability.
According to this invention, there is provided a disposable body fluid absorbent wearing article comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed between these top- and backsheets.
According to this invention the topsheet comprises plastic film layer sections each having upper and lower surfaces and a thickness of 0.001xcx9c0.05 mm, liquid-pervious openings defined between respective pairs of the adjacent plastic film layer sections and a first fibrous layer bonded to the lower surfaces of the plastic film layer sections and immediately underlying the openings, the topsheet having a Klemm""s water absorbency lower than 10 mm, each of the openings has a width of 0.05xcx9c1 mm so that a total open area thereof occupies 3xcx9c40% of a surface area of the topsheet, edges of the plastic film layer sections defining the openings being partially fibrillated so as to form a rising portion having the maximum height of 1.5 mm and component fibers of the first fibrous layer having a fineness of 0.5xcx9c20 dtex and a basis weight of 5xcx9c60 g/m2; and the core has a second fibrous layer being closely contiguous to the lower surface of the first fibrous layer and a third fibrous layer being closely contiguous to the lower surface of the second fibrous layer wherein the second fibrous layer has a Klemm""s water absorbency is lower than 35 mm but higher than a Klemm""s water absorbency of the topsheet by 15 mm or more and the third fibrous layer has a Klemm""s water absorbency of at least 35 mm but higher than the Klemms water absorbency of the second fibrous layer by 15 mm or more.